A county report released Monday added fuel to the debate over whether the operator of Los Angeles International Airport is adequately trying to spread the growth of commercial flights to other airports in the area.

Requested by the Los Angeles County Board of Supervisors in February, the study reviewed the efforts of Los Angeles World Airports to regionalize air traffic, a key requirement of a 2006 court settlement that ended a legal challenge to modernization plans at LAX.

"I'm somewhat disappointed. The report needs a more in-depth analysis of the regionalization issue," said Supervisor Don Knabe, who requested the review. "But in its own little way, it shows that there has not been a good faith effort by LAWA or any visible results at this point."

Knabe cited the severe decline of LA/Ontario International Airport while under the control of Los Angeles. Once among the fastest-growing regional airports in the nation, the passenger volume at Ontario has plunged from 7.2 million in 2007 to 4.2 million last year.

The downturn has prompted the city of Ontario and other Inland Empire officials to wrest control of the airport from Los Angeles. On Tuesday, the supervisors are scheduled to vote on an endorsement of the effort -- a move Knabe says he supports.

Los Angeles airport officials defended their record, saying the report acknowledges their work since 2006 to spread flights to other airports, especially Ontario.

"Our efforts clearly indicate [Los Angeles Mayor Antonio Villaraigosa's] strong commitment to a healthy regional air traffic system for all of Southern California," said Gina Marie Lindsey, executive director of the airport agency.

Lindsey has blamed Ontario's decline on the national economic recession, which has caused airlines to reduce service and shift flights to large aviation hubs such as LAX.

Issued by the county chief executive's office, the new report found that several developments have frustrated regionalization over the years, including the failure of a special commission to meet since 2008 and dramatic cuts in the marketing budget for Ontario from $2 million a year to $200,000.

The study included the views of Ontario city officials and the Alliance for a Regional Solution to Airport Congestion, a coalition of neighborhood groups and cities near LAX that don't want that airport to grow any larger. They asserted that the regionalization effort has been a failure and that more needs to be done to achieve that goal.

Researchers stated, however, that Los Angeles World Airports has spent $506 million for improvements at Ontario, generated numerous reports and presentations about regionalization, cut costs in an attempt to attract airlines to Ontario and met 171 times with carriers to discuss locating service there.

Researchers added that Los Angeles officials have considered various management alternatives at Ontario and tried unsuccessfully to bring service to LA/Palmdale Regional Airport, the control of which is being transferred to the city of Palmdale.

"There has been a significant debate on this issue," said Supervisor Mark Ridley-Thomas, who asked for the study along with Knabe. "There is no evidence to date that LAWA has violated the intent or the spirit of the settlement."